Vitamin D insufficiency increases bone turnover markers and enhances bone loss at the hip in patients with established vertebral osteoporosis

AIM The aim of this study was to determine whether the presence of vitamin D insufficiency increases bone turnover and enhances bone loss by examining the relationship between bone turnover markers and Bone mineral density (BMD) in vitamin D insufficient and vitamin D sufficient patients, with established vertebral osteoporosis. SUBJECTS 119 consecutive, active, community dwelling, elderly women were assessed over a 7-month period between the months of March to October. RESULTS There was a significant correlation between parathyroid hormone (PTH) and 25 hydroxyvitamin D (25(OH)D), r=-0.42 (P<0.01). The prevalence of vitamin D insufficiency was 26.9% (defined by a 25(OH)D ≥ 6.1 μg/l and ≤ 12 μg/l). This resulted in a statistically significant increase in bone turnover markers compared to the vitamin D sufficient group: bone alkaline phosphatase (P<0.05), osteocalcin (P<0.01), hydroxyproline (P<0.05), free deoxypyridinoline (P<0.05) and lower bone mineral density at the total hip (P<0.01). CONCLUSIONS These results show that there is a high prevalence of vitamin D insufficiency in the active community dwelling elderly with established vertebral osteoporosis presenting to clinical attention, which leads to increased bone turnover, decreased BMD at the hip and thus enhanced risk of further osteoporotic fractures in comparison with vitamin D sufficient subjects.